This base-catalyzed isomerization involves the following steps: 1. Deprotonation to form tetrahedral intermediate 1; 2. Collapse of the tetrahedral intermediate and bond cleavage to form enolate ion 2; 3. Proton transfer to form enolate ion 3; 4. Intramolecular aldol reaction to form tetrahedral intermediate 4. Write out the reaction on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 1.

Explanation:

The objective of this question is to show the stepwise reaction mechanism for the base-catalyzed isomerization. This mechanism is shown in the attached diagram below together with its intermediary and enolate ions.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.